/**
 * @file
 * SNMP Agent message handling structures.
 */

/*
 * Copyright (c) 2006 Axon Digital Design B.V., The Netherlands.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * Author: Christiaan Simons <christiaan.simons@axon.tv>
 */

#ifndef __LWIP_SNMP_MSG_H__
#define __LWIP_SNMP_MSG_H__

#include "lwip/opt.h"
#include "lwip/snmp.h"
#include "lwip/snmp_structs.h"
#include "lwip/ip_addr.h"
#include "lwip/err.h"

#if LWIP_SNMP

#if SNMP_PRIVATE_MIB
	/* When using a private MIB, you have to create a file 'private_mib.h' that contains
	* a 'struct mib_array_node mib_private' which contains your MIB. */
	#include "private_mib.h"
#endif

#ifdef __cplusplus
extern "C" {
#endif

/* The listen port of the SNMP agent. Clients have to make their requests to
   this port. Most standard clients won't work if you change this! */
#ifndef SNMP_IN_PORT
#define SNMP_IN_PORT 161
#endif
/* The remote port the SNMP agent sends traps to. Most standard trap sinks won't
   work if you change this! */
#ifndef SNMP_TRAP_PORT
#define SNMP_TRAP_PORT 162
#endif

#define SNMP_ES_NOERROR 0
#define SNMP_ES_TOOBIG 1
#define SNMP_ES_NOSUCHNAME 2
#define SNMP_ES_BADVALUE 3
#define SNMP_ES_READONLY 4
#define SNMP_ES_GENERROR 5

#define SNMP_GENTRAP_COLDSTART 0
#define SNMP_GENTRAP_WARMSTART 1
#define SNMP_GENTRAP_AUTHFAIL 4
#define SNMP_GENTRAP_ENTERPRISESPC 6

struct snmp_varbind {
	/* next pointer, NULL for last in list */
	struct snmp_varbind* next;
	/* previous pointer, NULL for first in list */
	struct snmp_varbind* prev;

	/* object identifier length (in s32_t) */
	u8_t ident_len;
	/* object identifier array */
	s32_t* ident;

	/* object value ASN1 type */
	u8_t value_type;
	/* object value length (in u8_t) */
	u8_t value_len;
	/* object value */
	void* value;

	/* encoding varbind seq length length */
	u8_t seqlenlen;
	/* encoding object identifier length length */
	u8_t olenlen;
	/* encoding object value length length */
	u8_t vlenlen;
	/* encoding varbind seq length */
	u16_t seqlen;
	/* encoding object identifier length */
	u16_t olen;
	/* encoding object value length */
	u16_t vlen;
};

struct snmp_varbind_root {
	struct snmp_varbind* head;
	struct snmp_varbind* tail;
	/* number of variable bindings in list */
	u8_t count;
	/* encoding varbind-list seq length length */
	u8_t seqlenlen;
	/* encoding varbind-list seq length */
	u16_t seqlen;
};

/** output response message header length fields */
struct snmp_resp_header_lengths {
	/* encoding error-index length length */
	u8_t erridxlenlen;
	/* encoding error-status length length */
	u8_t errstatlenlen;
	/* encoding request id length length */
	u8_t ridlenlen;
	/* encoding pdu length length */
	u8_t pdulenlen;
	/* encoding community length length */
	u8_t comlenlen;
	/* encoding version length length */
	u8_t verlenlen;
	/* encoding sequence length length */
	u8_t seqlenlen;

	/* encoding error-index length */
	u16_t erridxlen;
	/* encoding error-status length */
	u16_t errstatlen;
	/* encoding request id length */
	u16_t ridlen;
	/* encoding pdu length */
	u16_t pdulen;
	/* encoding community length */
	u16_t comlen;
	/* encoding version length */
	u16_t verlen;
	/* encoding sequence length */
	u16_t seqlen;
};

/** output response message header length fields */
struct snmp_trap_header_lengths {
	/* encoding timestamp length length */
	u8_t tslenlen;
	/* encoding specific-trap length length */
	u8_t strplenlen;
	/* encoding generic-trap length length */
	u8_t gtrplenlen;
	/* encoding agent-addr length length */
	u8_t aaddrlenlen;
	/* encoding enterprise-id length length */
	u8_t eidlenlen;
	/* encoding pdu length length */
	u8_t pdulenlen;
	/* encoding community length length */
	u8_t comlenlen;
	/* encoding version length length */
	u8_t verlenlen;
	/* encoding sequence length length */
	u8_t seqlenlen;

	/* encoding timestamp length */
	u16_t tslen;
	/* encoding specific-trap length */
	u16_t strplen;
	/* encoding generic-trap length */
	u16_t gtrplen;
	/* encoding agent-addr length */
	u16_t aaddrlen;
	/* encoding enterprise-id length */
	u16_t eidlen;
	/* encoding pdu length */
	u16_t pdulen;
	/* encoding community length */
	u16_t comlen;
	/* encoding version length */
	u16_t verlen;
	/* encoding sequence length */
	u16_t seqlen;
};

/* Accepting new SNMP messages. */
#define SNMP_MSG_EMPTY                 0
/* Search for matching object for variable binding. */
#define SNMP_MSG_SEARCH_OBJ            1
/* Perform SNMP operation on in-memory object.
   Pass-through states, for symmetry only. */
#define SNMP_MSG_INTERNAL_GET_OBJDEF   2
#define SNMP_MSG_INTERNAL_GET_VALUE    3
#define SNMP_MSG_INTERNAL_SET_TEST     4
#define SNMP_MSG_INTERNAL_GET_OBJDEF_S 5
#define SNMP_MSG_INTERNAL_SET_VALUE    6
/* Perform SNMP operation on object located externally.
   In theory this could be used for building a proxy agent.
   Practical use is for an enterprise spc. app. gateway. */
#define SNMP_MSG_EXTERNAL_GET_OBJDEF   7
#define SNMP_MSG_EXTERNAL_GET_VALUE    8
#define SNMP_MSG_EXTERNAL_SET_TEST     9
#define SNMP_MSG_EXTERNAL_GET_OBJDEF_S 10
#define SNMP_MSG_EXTERNAL_SET_VALUE    11

#define SNMP_COMMUNITY_STR_LEN 64
struct snmp_msg_pstat {
	/* lwIP local port (161) binding */
	struct udp_pcb* pcb;
	/* source IP address */
	ip_addr_t sip;
	/* source UDP port */
	u16_t sp;
	/* request type */
	u8_t rt;
	/* request ID */
	s32_t rid;
	/* error status */
	s32_t error_status;
	/* error index */
	s32_t error_index;
	/* community name (zero terminated) */
	u8_t community[SNMP_COMMUNITY_STR_LEN + 1];
	/* community string length (exclusive zero term) */
	u8_t com_strlen;
	/* one out of MSG_EMPTY, MSG_DEMUX, MSG_INTERNAL, MSG_EXTERNAL_x */
	u8_t state;
	/* saved arguments for MSG_EXTERNAL_x */
	struct mib_external_node* ext_mib_node;
	struct snmp_name_ptr ext_name_ptr;
	struct obj_def ext_object_def;
	struct snmp_obj_id ext_oid;
	/* index into input variable binding list */
	u8_t vb_idx;
	/* ptr into input variable binding list */
	struct snmp_varbind* vb_ptr;
	/* list of variable bindings from input */
	struct snmp_varbind_root invb;
	/* list of variable bindings to output */
	struct snmp_varbind_root outvb;
	/* output response lengths used in ASN encoding */
	struct snmp_resp_header_lengths rhl;
};

struct snmp_msg_trap {
	/* lwIP local port (161) binding */
	struct udp_pcb* pcb;
	/* destination IP address in network order */
	ip_addr_t dip;

	/* source enterprise ID (sysObjectID) */
	struct snmp_obj_id* enterprise;
	/* source IP address, raw network order format */
	u8_t sip_raw[4];
	/* generic trap code */
	u32_t gen_trap;
	/* specific trap code */
	u32_t spc_trap;
	/* timestamp */
	u32_t ts;
	/* list of variable bindings to output */
	struct snmp_varbind_root outvb;
	/* output trap lengths used in ASN encoding */
	struct snmp_trap_header_lengths thl;
};

/** Agent Version constant, 0 = v1 oddity */
extern const s32_t snmp_version;
/** Agent default "public" community string */
extern const char snmp_publiccommunity[7];

extern struct snmp_msg_trap trap_msg;

/** Agent setup, start listening to port 161. */
void snmp_init(void);
void snmp_trap_dst_enable(u8_t dst_idx, u8_t enable);
void snmp_trap_dst_ip_set(u8_t dst_idx, ip_addr_t* dst);

/** Varbind-list functions. */
struct snmp_varbind* snmp_varbind_alloc(struct snmp_obj_id* oid, u8_t type, u8_t len);
void snmp_varbind_free(struct snmp_varbind* vb);
void snmp_varbind_list_free(struct snmp_varbind_root* root);
void snmp_varbind_tail_add(struct snmp_varbind_root* root, struct snmp_varbind* vb);
struct snmp_varbind* snmp_varbind_tail_remove(struct snmp_varbind_root* root);

/** Handle an internal (recv) or external (private response) event. */
void snmp_msg_event(u8_t request_id);
err_t snmp_send_response(struct snmp_msg_pstat* m_stat);
err_t snmp_send_trap(s8_t generic_trap, struct snmp_obj_id* eoid, s32_t specific_trap);
void snmp_coldstart_trap(void);
void snmp_authfail_trap(void);

#ifdef __cplusplus
}
#endif

#endif /* LWIP_SNMP */

#endif /* __LWIP_SNMP_MSG_H__ */
